In the production of profiled bodies such as, for example, disc carriers of clutches, toothed-belt discs or similar workpieces having a cylindrical basic structure, high levels of accuracy and precision are frequently required. In particular, accuracy and the surface quality are important.
Described in DE 20 17 709 is a method used for producing the above-mentioned components. A special rolling die enables the workpiece to be produced from a blank having a smooth outer contour by means of a press, each press stroke shaping a workpiece from a blank. Upon each press stroke, a rolling operation is executed, in which the profiled rollers impress the wanted external profile into the circumferential surface of the workpiece. The profiled rollers in this case are arranged in a bottom die along the circumference of the workpiece to be worked. If the workpiece is pressed between the rollers by means of a top die attached to the ram of the press, these rollers are supported on support rollers having a corresponding bearing system. The bottom die can be constructed to be rotationally symmetrical, the individual profiled rollers that produce the profile of the workpiece being distributed regularly and at a uniform angle in relation to each other along the circumference of the workpiece. As a consequence thereof, and owing to the resultant rotationally symmetrical apportioning of forces during a forming process, the individual grooves produced by the respective profiled rollers are practically the same as each other. In particular, an outer contour having no offset is achieved.
The disadvantage of this method is that the rotation, and therefore the rolling of the profiled rollers, is produced only by the forces acting between the workpiece and the profiled roller during the forming process. There occurs as a result non-definable slip of the profiled roller in relation to the workpiece. In the case of continuous profiles that are uniform in the longitudinal direction, this slip does not normally result in problems. If the profile is irregular in the longitudinal direction, however, for example having a web, in the middle of the profile length, extending transversely relative to the longitudinal groove, the slip results in dimensional inaccuracies, and thus in quality defects.
Disclosed in DE 195 06 391 A1 is a method in which the profiled rollers are driven in such a way that the circumferential speed in the forming region matches the speed of the workpiece. The drive is effected by transmission of the ram motion to the profiled rollers via transmission means, such as toothed racks and toothed wheels. This method, or the arrangement of the above-mentioned transmission means, reliably prevents the slip between the profiled rollers and the workpiece.
The disadvantage of this method is the very resource-intensive structure and the resultant high costs of the device. It is further disadvantageous that the multiplicity of transmission means necessitates a large structural height of the device.
A device for producing longitudinal grooves in a cylindrical workpiece is likewise described in EP 0 006 137 A1. In the case of this solution, the forming process is effected, not by profiled rollers, but by segmental discs. The segmental discs are not driven. The outer contours of the segmental discs roll on the surface of the downwardly-moving workpiece. As a result, the segmental discs move on a circular path curve. The positions of the segmental discs at the start of the engagement are defined by spring-actuated retaining pins. The segmental discs are connected to a housing by means of a spherical sliding bearing system. Since the segmental discs are moved exclusively by the forces acting during the forming process and do not have a drive synchronized with the ram motion, a slight slip between the segmental disc surface and the workpiece is unavoidable. In addition, a precisely defined starting position of the segmental discs for the forming process cannot be realized. This is a crucial disadvantage, especially for workpieces having grooved profiles that are irregular in the longitudinal direction.